Automatic train-control system



Oct; 8, 1929. c. s. BUSHNELL 1,730,843

AUTOMATIC TRAIN CONTROL SYSTEI Original'Filed May 18, 1921 FIGJ 0 TIMERETARDED T4 BlAszb CLOGK-WISE lNVE TOR fiTORNEY Patented Get. 8, 1929UNETED STATES PATENT OFFICE CHARLES S, BUSHNELL, OF ROCHE$TER, NEN YORK,ASSIGNOR TO GENERAL RAILWAY SIGNAL COMPANY, OF ROCHESTER, NEW YORKAUTOMATIC TRAIN-CONTRUL SYSTEM Original application filed May 18, 1921,Serial No. 470,552. Divided and this application file-'1 February 25,

This invention relates to automatic train control systems for railroads,and more particularly to the car equipn'ient of such systems, and is adivision. of application No.

$70,592 filed May 18 1921,

' proper performance of the automatic apparatus. he may perhaps be morelax in his observ nce of the usual block signals, since he will feelthat the automatic devices will in some way give a special warning orapply the brakes automatically in case of danger. it is consideredobjectionable, however, to take away the vigilance of the engineer,because modern block signal systems are very r0 fable and cflicient, andengineers as a rule a e highly trained, experienced and carefuloperators, so that if the engineer becomes negligent in observing thesignal indications or in acting upon them, there is sacrificed a largeproportion of the safety of train operation at present obtained by thesignal systom and the care with which the engineers ordinarily observeand obey the signals. It is evidei that the ultimate safety of the trainis more d if the automatic train control system is supplementary to theblock signal stem and the vigilance of the engineer, rather than as asubstitute therefor; and if the engineer can he encouraged or forced toobserve and, act upon the indications of the traclm'ay signals, aserious accident can result only when signal system, the engineer, an dthe train control apparatus all fail at the same time.

ll'ii these considerations in mind, one obof the present invention is toprovide a cm of automatic train control in which a penalty isauton'iatically enforced if .ieer Fails to observe a caution or stopsignal, and fails to take some appropriate action in recognition of suchunfavorable "l indication. Iii: the engineer observes "Ication and actsaccordingly, the pen not be enforced and the engineer is ouragco toobserve and act upon the mdications. According to the-present Serialinvention the penalty in question consists in causing an automatic brakeapplication, or in imposing some suitable form of control, whichpersists until a reset device is manually operated. c This reset deviceis preferably nrade accessible only from the ground or is arranged insome other way so that it cannot be used without great trouble andannoyance, and. is also protected so that it cannot be maliciouslystoned down, or manipulated in such a wav as to avoid the penalty anddefeat the purpose of the invention.

This invention is in the nature of an improvement upon the systemdisclosed and claimed in the application of \V. K. Howe, Ser. No.427,110, filed July 80, 1925; and the patent to Howe No. 1,551,515datedAugust 25, 1925.

in the accompanying drawings;

Fig. 1 is a diagrammatic view of one arrangement of tracl zway circuitsapplicable to the present invention;

Fig. 2 is a diagrammatic view of a car equipment, the parts and circuitsbeing shown more particularly with the object of making the functionsand mode of operation easy to understand, th an with the idea of showingthe precise construction and arrangement of parts preferably employed inpractice; and,

Fig. 3 illustrates a modified wiring arrangement and construction of thecar equipment.

Referring to Fig. 1, the track rails 1 of the railroad track are dividedby insulated clubs 2 into blocks in the usual way, one block N with theadjacent ends of two other blocks ll and O being shown; The parts andcircuits associated with the several blocks are the same, and forconvenience these will be given like reference characters withdistinctive eX- ponents. Each block is provided with "the well-luiownnominally closed track circuit commonly used in block signal systems,comprising a track battery 3 and a track relay 1-. The usual trackwayfined signals S are illustrated conventionally, and since they may takevarious forms, such as semaphore nals or color light signals, and may becontrolled in any of the welhknown ways, no attemnt has been made toillustrate their conclearances will permit. on

trol circuits and devices, it being understood that these signals willgive the usual clear, caution, ant. stop indications and will be obeyedin accordance with the rules in force on the particular railroad.

In the particular embodiment oi? the invention illustrated, it isassumed that the transmission or communication of the de siredcontrolling impulses or inih ences from the trackway to the movingtrains for governing the automaticapparatus thereon in accordance witht'ailic conditions, is accomplished inductively, that is, through anintervening air gap. ,v "hile this inductive type of impulsetransmitting means may take any one of various well-known terms, thereis illustrated an arrangement comprisa track element T.

The track element 'l comprises in genera a U-shaped yoke or core 5 ofmagnetic material, with coils G thereon. The coils (3 are wound andconnected in series in such a way that the electro-motive-tor"esgenerated in he respective coils by flux passing through the yoke 5 arecumulative or additi. TllQSQ track elements T may be located and controlled in va 'ious ways, dependent on, on trattic conditions ahead, butin the p imilar arrangement shown in Fig. 2, track element T is locatedat the entrance to each block, a short distance in the rear of theinsulated joints 2, the normal direction of tmtic being from left toright, as indicated by the arrow. The coils 6 of this track element Tare connected in series in a normally closed circuit of low resistance,including the front contact of a line relay D. The energizing circuitfor the line relay D includes a front contact of the track relay a ofthe correspoocrn block, and a front Contact of the track relay 1- of thenext block in advance. Thus, the coils 6 oi the track element T at theent 'ance to a given block are in a closed circuit under clear traliicconditions, but are open-circuited under caution or stop conditions,that is, when the corresponding block or the next block in advance isoccupied. These trail elements T may be located crosswise of the trackbetween the track rails shown, r lengthwise, between or outside ofeither track rail, and in other ways, provided the car e ment isdisposed accordingly.

The car element Y, see 2. comprises a simila til-shaped core or yoke 7of n aenetic material and is supported in some manner from the frame ofthe locomotive other vehicle, so as to pass directly over the trackelement T, as show in The air between the pole pieces of the trackelement T and the car element Y is pre eably made as shor' as equipmentand 7 is a coil 8 conven'ently te coil and on the otherle oother coil 9,conveniently termed the secondary coil.

In connection with the car element tl pi'eierabl y employed an electronampl "11g relay of the thermionic or vacuum bill) type, 1 an audion,

COll llllOlrly KHOWD 3.. and which will be referred to by that i aine asa matter of convenience. This audio eing welhknown in the art, isillustrated convennnprises a filament F, a grid n controls a car relayThe notion of this relay adaptii a train control system ot the typeshown in rnis no part or the present in S0 vcntion, and this relay isshown conventake may *arious ts pa ticular construction *1 the presentinvention, this rated convention device, shown in 'f'DQ JlC valve, may

i apply the brakes nor operr tron inn, t is necessz ry to provide thedevice *h are broken when said in the conventional lustrated in Fig. 2,the core or the device carries an insulated hich t. hle lined contactsconventioi ally is arrows) and thus A r L1 through said contacts i T 1J- energized. (i hen tea t is 'e-en rghced, its core or plunger l by iair pressure or the like,

ement with .ied contacts. hereby brealt' rough said ontact;

ith the invention m nd a d ed 'o s. e

. T as t v ntior all Y r Jr r b so lLCll of is in erotectir 5 case r without ut p rea:

' rangemont has been illustrated.

sistance of someone else, the purpose to g to make the operation of thisreset switch Q so objectionable to the engineer that he Wlll voluntarilyobserve and obey the signals to avoid the necessity of such operation.The hold-oil switch or device H is arranged in the cab in a convenientposition to be operatod by the engineer; and to prevent its impropermanipulation, there is provided as-- sociated mechanism which preventsthe device being held closed or fastened down. A holdo;ll' device ofthis character is disclosed in a generic form in the Howe applicationabove mentioned, and it is to be understood that no claim is made hereto the generic form of the invention disclosed in the said application.

The circuit connections between the audion, the relay R, and the controldevice K are sul ject to considerable modification in practice, butsince any form of connections suitable for causing operation of therelay B when the car passes an active track element, is applicable tothe present invention, only one typical ar- The lilanient F of theaudion is heated by the battery A. 'l. he grid G is connected in circuitwith the secondary coil 9 and the battery C by wires 38 and 39, so thatelectro-motiv, forces induced the secondary coil. will vary the gridpotential. The plate P is connected in circuit with the relay li, afront contact there of, and the ba.;teries B and C. Referring to Fig. 2this plate circuit may be conveniently traced as follows:com1nencing atthe positive terminal. of battery B, wires 40, all, 42. front contact4-3 of relay R, wires 4% and 4.5, relay R, and wire 46 to plate P.

The primary coil 8 is normally energized from batteries 13 and C throughthe train con trol. device K and the front contact 43 of the relay R,this circuit being traced as follows:commencing at battery B, wires 4.0,4-1 and 42, front contact 4-3 of relay ll, wires l4c and 47, resetswitch 11 and its closedcontact, wire a8, device K, wire 4C9, primarycoil 8, and wire 51 to the battery C.

Operation.Tho battery C normally produces a positive potential upon thegrid G with respect to the average potential. of the filament F, andthus permits current to How in the plate circuit and maintain relay Renergized. The current through the primary coil 8 produces amagneto-motive-force tending to send flux through the car yoke 7, thisflux passing in part tln-ough the l cgs of said yoke and in part throughleakage paths. The yoke 7 may be said to constitute a partial magneticcircuit with an air gap of relatively high reluctance.

Assume that the car passes over track element T having its coils 6open-circuited, corresponding to dangerous t *aiiic conditions ahad,that is, when a stopping impulse should be transmitted. The trackelement in this condition presents in effect a magnetic loop for theyoke7 on the passing car, and acts to complete the partial magnetic circuiton the car and change its reluctance, the luctance decreasing from anormal to a minimum, and then baclr to normal, as the car approaches andrecedes from the tracl: element. This change in reluctance vari the fluxpassingthrough the secondary coil 9, thereby inducing an electro-lnotiveiiiorce in said coil, first in one direction and then in the other. Onehalf of this wave of induced E. M. F. in the secondary coil 9, eitherthe first or secon d half depending upon the connections, opposes thevoltage of the battery C and reduces the potential on the grid G. Thenormal potential on the grid G being thus decreased, the current flowingin the plate circuit through the relay it is likewise decreased, and theparts are so proportioned and adjusted that the current in the relay llis reduced in this way below the amount required to hold its frontcontact 43 closed. Vlhen the front contact opens, the "rain controldevice K is (lo-energized, and the circuit through relay R is alsobroken at its contact $3, with the result that said relay can not againpickup when the grid potential again becomes normal.

Suppose that the coils G of the track element '1 are included in aclosed circuit of low resistance, corresponding to clear oraliicconditions. When the car element Y passes over a track element in thisclear or inactive condition, the relay It is not operate b pause thecoils 6 0n the track element oppose or choice back the passage oi fluxthrough the yoke 5 due to the counter-elcctro-mohive-forces induced insaid coils, with the result that there is little change in flux throughthe secondary coil 9 and the relay is not operated.

The operation so far described is that which is characteristic of thetype of system illustrated, this particular systen'i being merelyillustrative of one suitable for the application of the presentinvention, and being disclosed and claimed in other applications.Arrangements to prevent improper operation of the car equipment by trackrails or other masses of iron along the track, and various otherexpedients that may be necessary or desirable in a complete system, arenot material to the present invention, and being; fully disclosed inother applications, are not herein illustrated. Further, the operationso far described does not take into consideration the action of thehold-oil device H, the reset switch Q, and associated parts constitutingthe. subject-matter of the presentinvention.

As previously explained, the purpose of the present invention is toprovide an ar rangement for enforcing vigilance on the part oi theengineer in observing and acting upon the indications of the fixedsignals. T he engineer is supposed to watch out for the vaand it one ofthese sigis intended that he device E1 While racl: elen eni, t the conar the 0,. it track e rra will not erite "he proper time, and piara usi: Will b 1 eration as the train rack element, thereby s ti on andconstruction is si by said apoaratus upon the cs maintain il theresetira swit ile only it. so in t he s ope 1 o? obiectio (ill nat idevice in recosni-rio' signal, rather than he s" 'al trouble, annoyance,sting; the reset switch here that the penalty, l, i =0 s1 oak, andconcurren ""i l naturally have more subsec u 59 a recorder or device n Vconjanction with the system described to provide a check which theengineer ierfornis l i *ier' no t e arrangement e 1' pr *enting effecanarrange handle 12 of revents de-cne" ,1 ,1 J! c 1. u i t is iiont conthehold-off device l-i, 5- normally closed contacts 10 ot' the device lwire su 11 and its closed contact, Wire ib, device l1, wire it, primarycoil 8 and to battery C and b to battery ei'i'ect this circuit comprisesin part a around the front eonta 43 of the reiay that although saidfront contact opens, ice K is n ntaiiied energized. if the engineeroperates the hold-oi crevice H the Whistle i is sounded when the frontot' the relay R opens, said front ether with Wires ii, 42, i i and l'i'a low resistance shunt around portion comprising Wire 52, the tneWhistle V, 53, 25-2(i, 16 1S, nd depriving the winding of ective currentuntil said i ont- 'i he whistle l thus serves 1 the track eleinent habeen the hold-oil device H may be :;o, the sounding of the Whistle 7signifies seat the train control equipment 'orl' ng properly, and thatan automatic A i the device K would have occurred if the hold-off devicehad not been ed. When the relay R opens its front this contact Will beat once closed as i s the nor nal current again flows in the circuit,because the front contact of 1 through the Whistle VJ, the Winding ofthe whistle il being made in practice oi low enough resistance to permitthe relay R to pick-up with said Winding i1 series therewith.

It the engineer does not operate the hold-o device H at the proper time,the relay R drop. and (lo-energizes the device K, imposing tile desiredcontrol upon the train, and also opens the contacts 10 or" said deviceso that subsequent operation of the hold-oil device H is not eiiectiveto restore the relay R. The relay E- can only be restored by operating"the reset switch ran the reset switch C5 is actuated to close itsnormally opened contacts, tie relay R is energized by cir uit which maybe traced as tollowszcoinn encinr;- at the batte B, Wires d0, 4&1 and56, switch 11, Wires i7 and 45, relay R and Wire to the )l te i. Yihenrelay is thus picked up, t is held up t irough its own frontcontact 43and toe switch Q may be restored to normal.

It Will be noted that when the switch G is ted, ithrealzs the energizingcircuit for rice K, so that unless restored to the 1 position, the trainis not released from he control imposed by the device ii. Thus, l resetswitch Q is protected against ini- =ope: manipulation, and can not befastened owi, otherwise the train control device K will be operated andprevent the usual train movement.

In the form shown in Fig. 2, the normally closed contacts 25*26 of thehold-oil device H are included in the wire 53 of the hold-0d circuit andare also included in series wito the normally opened contacts 16-18 ofsaid liolrho'lt device. 'llhe cam 22 of this acknowlin, device Tiioscdii'iacloclm'iscdirectie 1, but is held nst rotation by the pinthereof ei ie handle 12, the spring 15 to overcome the fierce it thehandle 12 is held down, the cam 22 rotates in a clocl=:wir-:o directionat a restricted rate determined by a suitable time controlled device,more specifically described in the parent application. if the engineerholds down the handle 12 too long, the contacts 2526 open, for r isonsapparently from the shape oi the cam 22, rendering the device Hineii'ective and causing automatic operation of the device K at the nextactive track element T. In other words, while the engineer may fastendown the handle 12 otthis hold-oii device without immediate penalty,this act will the same time destroy the effectiveness or. said holdso'll device and consequently maize it useless to fasten down the handle'12. In short, the engineer must operate the hold-oil device at eachsignal and at the time he is passing that signal, otherwise anautomaticoperation of the train control device K will result.

3 shows a modified. arrangement of the parts and circuits constitutingthe invention, in which the operation of the hold-oil device H preventseffective action of the cautionary impulse by maintaining the Controlrelay R energized. .ln this modified arrangement, when the handle 12 ismoved down and contacts 1618 are closed, the relay R ma; he maintainedene'ai izaed independently of the decrease in our] art between the plateand jtilament of the aud on by an auxiliary energizing circuit follows:commencing at an in tcrmcdiate tap oi? the battery I wire 70, adjustableresistance 71, wire 72, contacts 1ti-1S. wire 73, contacts 25 and 26,wire 7435, relay R, wires 42:; and 44, front contact 43, wires 42 and.40 to the end tap oi? the battery he voltage of the section of thebattery 7% inchided in this circuit, together with the resistance 71, isproportioned with. regard to the resistance o1 the audion between theplate and filament, so that the current supplied to the relay Rcorresponds substantially with its normal Wei-lung current whengoverned. by the audion.

The modified circuit arrangement shown in Fig. 8 has the same general.characteristics of operation that have been descriliied. As the eerapproaches caution signal, he may down the 12 and clc e contacts i, trom*a over a coherent form of holdiwwledg einent arrangement is provided.in Fig. 3 the elements 52, XV, 53, 54, i0 and of the hold-oil moansshown in Fig. 2 ha ve been omi'i'iitted, and the normally closedcontacts L526 and the normally opened contacts 16 18 of the hold-oildevice H have tween emiloyed to provide a distinct circuit formaintaining the relay R energized irrective otthe action of theamplyfying device F, i i, if upon passage oi a train by a control poi t.will he noted that upon operation of? the handle 12 and for apredetermined led at time thereafter both pairs of concts l6 and 25 26are closed, and the mine hold-oil circuit is completed:-

at the plus side of battery B, wires ell.) and 42, contact 13, wire4.4:, winding of relay ll, wire fl57el, contacts 26-25, Wire 73,contacts 1816, wire 72, resistance 71, wire back to the midpoint ofbattery B. The closure of this circuit maintains the relay R energizedeven though the plate circuit in the amplifier drops to zero.

This mooified form of Fig. 3 has its normally closed contacts 2526included in series with its normally open contacts 1618, similar to thearrangen'ient shown in Fig. 2 of this application, and except for thechange of location of the normally closed contacts 25-26 this modifiedform (Fig. 3) is the same as original Fig. 8 of the parent application.

Having thus shown and described my invention, it is to he understoodthat my invention is not limited to the specific arrange ments shown anddescribed.

ii hat I claim isz 1. In an automatic train control system, anelectromagnetic brake control device on a vehicle, a relay governingsaid device, traflic controlled means 'for controlling the relay, andn'ianually operable means adapted to prevent operation of the relay andhaving a limited time of etl'ective operation, such means includinnormally open and normally closed contacts in series.

In a train control system; cooperating (rack and car-carried elements adevice for applying the car brakes when initiated; stick control ingmeans for initiating said device 'ail'e luences til closed contacts inseries with each other, operable to prevent the said affecting ot' thecontrolling means by said trackvay influences, said acknowledging meansincluding means automatically operable after a predetermined timeinterval from operation thereof, to cause opening of the normally closedcontacts; and reset means, When operated, initiating said device andclosing a pick up circuit for said stick controlling means.

3. In an auton atic train control system of the irermittent inductivetype, the combination with a control relay on the car connected 1 astick circuit including its ovvn front contact, of tracl-Ivvay means atspaced control points the traclixvay tor inductively through anintervening air gap die-energizing said control relay upon passage ofsaid car under adverse tra'liic conditions, an acknowledging deviceincluding normally closed and normally open contacts constructed whenoperated to close the normally open contacts immediately and open thenormally closed contacts a predetermined interval of time after suchoperation, and a shunting circuit for preventing said traclnvay meansde-encrgizing said control relay including said normally open contactssaid normally closed contacts and a signal in series, whereby saidsignal is rendered active upon the reception of control influence fromthe traclrWa-y and said control relay is maintained energized it said aclnon'ledgin device has been operated.

In testimony whereof I atiiX my signature.

oneness s. BUSHNELL.

